The present invention relates to a drive unit, an optical unit, an imaging apparatus, and an endoscope, in which a voice coil motor is used to drive a movable part for advanceable/retractable movement.
An imaging apparatus such as a digital camera includes a drive unit for axial movement of a lens unit including lenses and a lens frame for holding the lenses in place. The drive unit is mounted on a guide member such as a lens barrel in such a way as to be movable in the optical axis direction, and the lens unit is axially moved by a driving source such as a motor for focal length adjustment, focusing, etc. A voice coil motor (VCM) is used as that driving source. The voice coil motor includes a coil and a permanent magnet, and there is an electromagnetic force generated by electric current flowing through the coil and a magnetic field created by the permanent magnet. The generated electromagnetic force allows for axial movement of the lens unit. To boost up the electromagnetic force and efficiently transmit it to the lens unit, a plurality of coils and a plurality of permanent magnets are occasionally used (see Patent Publications JP(A) 02-301023 and JP(A) 06-189518).